The use of sliding glass windows is common, in particular with motor vehicles. Such windows use a motor in combination with a window switch to slide the window from a closed position to a plurality of open positions. Around the outer edge of at least part of the window pane is a seal that provides a desirable watertight and in some instances airtight seal around the window pane. The seal allows for an edge portion of the window pane to fit at least partially within and provides contact therebetween in order to prevent water, air and the like from passing between the seal and the window pane. However, the seal between the window and the seal material results in a frictional force that must be overcome when the window is moved from a stationary position. Thus the better the seal, the higher the friction between the seal material and the window, and thus the greater the power required to move the window. An increase in the power required to move the window is in contradiction to desirable lightweight motors that have minimal electrical, hydraulic or pneumatic input power requirements. As such, a seal that affords for a decrease in friction prior to moving the window from a stationary position would be desirable.